Application of Gel Dosimetry

A special issue of Gels (ISSN 2310-2861). This special issue belongs to the section "Gel Chemistry and Physics".

Deadline for manuscript submissions: 31 December 2025 | Viewed by 1475

Special Issue Editors


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Guest Editor
Department of Energy, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
Interests: gel dosimetry; radiation chemistry

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Guest Editor
Department of Energy, Politecnico di Milano, 20133 Milano, Italy
Interests: nuclear waste management; development of treatment and conditioning methods for challenging nuclear waste
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Special Issue Information

Dear Colleagues,

The increasing complexity of modern radiotherapy necessitates improved performance from dosimetric systems used for quality assurance. In recent decades, gel dosimeters have emerged as a promising technology for the experimental validation of individualized, complex treatment plans. Clinical and metrological interest in these devices is motivated by their high tissue equivalency and inherent three-dimensional radiation response. Notably, gel dosimeters might enable the manufacturing of personalized anthropomorphic phantoms, accurately replicating patient anatomy and tissue inhomogeneities, which is crucial for individualized dosimetry.

The inherent multidisciplinary nature of gel dosimetry, spanning medical physics, radiation chemistry, and advanced imaging, has fueled significant interest from researchers. Current research focuses on developing novel gel formulations with reduced toxicity, enhanced stability, and adjustable sensitivity, as well as on the validation of gel measurements with respect to reference data. Simultaneously, the optimization of readout techniques, also leveraging advanced imaging modalities, is also being actively pursued. However, challenges such as achieving accurate three-dimensional absolute calibration, ensuring response reproducibility, maintaining spatial and temporal stability, and mitigating quenching effects with high-LET particles still hinder the widespread clinical adoption of gel dosimeters.

Despite these obstacles, ongoing research offers significant opportunities for fundamental scientific advancement, potentially solidifying gel dosimetry's role in the future of radiation therapy quality assurance.

For this Special Issue, we invite submissions covering all aspects of gel dosimetry, including experimental studies on novel concepts and formulations, investigations into radiation chemistry, optimization and validation campaigns, advancements in imaging techniques, and computational studies.

Dr. Gabriele Magugliani
Dr. Eros Mossini
Guest Editors

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Keywords

  • radiotherapy
  • dosimetry
  • gel dosimetry
  • quality assurance
  • polymer gels
  • radiochromic gels
  • dosimetric phantom
  • radiation chemistry

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Published Papers (3 papers)

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Research

14 pages, 7047 KB  
Article
The Potential of Dosimetry and the Visualization of Microbeam Arrays in NIPAM Gel at the PETRA III Synchrotron
by Thomas Breslin, Malin Kügele, Vincent de Rover, Stefan Fiedler, Tobias Lindner, Johannes Klingenberg, Guilherme Abreu Faria, Bernd Frerker, Frank Nuesken, Sofie Ceberg, Crister Ceberg, Michael Lerch, Guido Hildebrandt and Elisabeth Schültke
Gels 2025, 11(10), 814; https://doi.org/10.3390/gels11100814 - 10 Oct 2025
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Abstract
Spatially fractionated radiotherapy (SFRT) is emerging as a powerful tool in cancer therapy for patients who are ineligible for treatment with clinically established irradiation techniques. Microbeam radiotherapy (MRT) is characterized by spatial dose fractionation in the micrometre range. This presents challenges in both [...] Read more.
Spatially fractionated radiotherapy (SFRT) is emerging as a powerful tool in cancer therapy for patients who are ineligible for treatment with clinically established irradiation techniques. Microbeam radiotherapy (MRT) is characterized by spatial dose fractionation in the micrometre range. This presents challenges in both treatment planning and dosimetry. While a dosimetry system with a spatial resolution of 10 µm and an option for real-time readout already exists, this system can only record dose in a very small volume. Thus, we are exploring dosimetry in an N-isopropylacrylamide (NIPAM) gel as an option for 3D dose visualization and, potentially, also three-dimensional dosimetry in larger volumes. In the current study, we have recorded the geometric patterns of single- and multiport irradiation with microbeam arrays in NIPAM gel. Data for 3D dose distribution was acquired in a 7T small animal MRI scanner. We found that the resolution of the gel is well suited for a detailed 3D visualization of microbeam patterns even in complex multiport geometries, similar to that of radiochromic film, which is well established for recording 2D dose distribution in MRT. The results suggest that a dose–response calibration is required for reliable quantitative dosimetry. Full article
(This article belongs to the Special Issue Application of Gel Dosimetry)
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13 pages, 2731 KB  
Article
Suitability of Polyacrylamide-Based Dosimetric Gel for Proton and Carbon Ion Beam Geometric Characterization
by Riccardo Brambilla, Luca Trombetta, Gabriele Magugliani, Stefania Russo, Alessia Bazani, Eleonora Rossi, Eros Mossini, Elena Macerata, Francesco Galluccio, Mario Mariani and Mario Ciocca
Gels 2025, 11(10), 794; https://doi.org/10.3390/gels11100794 - 2 Oct 2025
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Abstract
Experimental measurement of dose distributions is a pivotal step in the quality assurance of radiotherapy treatments, especially for those relying on high delivery accuracy such as hadron therapy. This study investigated the response of a polymer gel dosimeter to determine its suitability in [...] Read more.
Experimental measurement of dose distributions is a pivotal step in the quality assurance of radiotherapy treatments, especially for those relying on high delivery accuracy such as hadron therapy. This study investigated the response of a polymer gel dosimeter to determine its suitability in performing geometric beam characterizations for hadron therapy under high-quenching conditions. Different extraction energies of proton and carbon ion beams were considered. Gel dose–response linearity and long-term stability were confirmed through optical measurements. Gel phantoms were irradiated with pencil beams and analyzed via magnetic resonance imaging. A multi-echo T2-weighted sequence was used to reconstruct depth–dose profiles and transversal distributions acquired by the gels, which were benchmarked against reference data. As expected, a response-quenching effect in the Bragg peak region was noted. Nonetheless, the studied gel formulation proved reliable in acquiring the geometric characteristics of the beams, even without correcting for the quenching effect. Indeed, depth–dose distributions acquired by the gels showed an excellent agreement with measured particle range with respect to reference values, with mean discrepancies of 0.5 ± 0.2 mm. Single-spot transverse FWHM values at increasing depths also presented an average agreement within 1 mm with values determined with radiochromic films, thus supporting the excellent spatial resolving capabilities of the dosimetric gel. Full article
(This article belongs to the Special Issue Application of Gel Dosimetry)
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14 pages, 1097 KB  
Article
Modeling the Impact of Viscosity on Fricke Gel Dosimeter Radiolysis: A Radiation Chemical Simulation Approach
by Sumaiya Akhter Ria, Jintana Meesungnoen and Jean-Paul Jay-Gerin
Gels 2025, 11(7), 489; https://doi.org/10.3390/gels11070489 - 24 Jun 2025
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Abstract
The Fricke gel dosimeter, a hydrogel-based chemical dosimeter containing dissolved ferrous sulfate, measures 3D radiation dose distributions by oxidizing Fe2+ to Fe3+ upon irradiation. This study investigates the variation in Fricke yield, G(Fe3+), from a radiation–chemical perspective in [...] Read more.
The Fricke gel dosimeter, a hydrogel-based chemical dosimeter containing dissolved ferrous sulfate, measures 3D radiation dose distributions by oxidizing Fe2+ to Fe3+ upon irradiation. This study investigates the variation in Fricke yield, G(Fe3+), from a radiation–chemical perspective in both standard and gel-like Fricke systems of varying viscosities, under low- and high-linear energy transfer (LET) conditions. We employed our Monte Carlo track chemistry code IONLYS-IRT, using protons of 300 MeV (LET~0.3 keV/µm) and 1 MeV (LET~25 keV/µm) as radiation sources. To assess the impact of viscosity on G(Fe3+), we systematically varied the diffusion coefficients of all radiolytic species in the Fricke gel, including Fe2+ and Fe3+ ions. Increasing gel viscosity reduces Fe3+ diffusion and stabilizes spatial dose distributions but also lowers G(Fe3+), compromising measurement accuracy and sensitivity—especially under high-LET irradiation. Our results show that an optimal Fricke gel dosimeter must balance these competing factors. Simulations with lower sulfuric acid concentrations (e.g., 0.05 M vs. 0.4 M) further revealed that G(Fe3+) values at ~100 s are nearly identical for both low- and high-LET conditions. This study underscores the utility of Monte Carlo simulations in modeling viscosity effects on Fricke gel radiolysis, guiding dosimeter optimization to maximize sensitivity and accuracy while preserving spatial dose distribution integrity. Full article
(This article belongs to the Special Issue Application of Gel Dosimetry)
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